Physics 202 Homework, Day 08: Chapter 15: #18,21,27, 39 ü 18. (a) Determine the electric field strength at a point 1.00 cm to the left of the middle charge in the figure below. (b) If a -2.00 µC charge is placed at this point, what are the magnitude and direction of the force on it? ü 21. A charge of -5.0 nC is at the origin, and a second charge of 7.0 nC is at x = 4.00 m. Find the magnitude and direction of the electric field halfway between the two charges. ü 27. In the figrure below, determine the point (other than infinity) at which the total electric field is zero. 2 Day_08_sol.nb 27. In the figrure below, determine the point (other than infinity) at which the total electric field is zero. ü 39. A Van de Graaf generator is charged so that a proton at its surface accelerates radially outward at 1.52 x 1012 m/s 2 . Find (a) the magnitude of the electrid force on the proton at that instant. [You will need to look up the charge and mass of a proton for this part.] (b) the magnitude and direction of the electric field at the surface of the generator. ü